KR20110036353A - Solar cell and method of fabircating the same - Google Patents

Abstract

PURPOSE: A solar battery and manufacturing method thereof are provided to connect lower electrode patterns of a bad cell area each other, thereby using the other cells except the bad cell. CONSTITUTION: A plurality of solar battery cells is formed on a substrate. The solar battery cells comprise a rear electrode pattern(200), a light absorbing layer, a buffer layer, and a front electrode layer. A connection electrode(600) electrically connects rear electrode patterns of a bad cell area(370) of the solar battery cells. The rear electrode patterns of the bad cell area are exposed. The exposed rear electrode patterns are electrically connected.

Description

SOLAR CELL AND METHOD OF FABIRCATING THE SAME}

An embodiment relates to a solar cell and a manufacturing method thereof.

Recently, as energy demand increases, development of a solar cell converting solar energy into electrical energy is in progress.

In particular, CIGS-based solar cells that are pn heterojunction devices having a substrate structure including a glass substrate, a metal back electrode layer, a p-type CIGS-based light absorbing layer, a high resistance buffer layer, an n-type window layer, and the like are widely used.

In such a solar cell, a plurality of cells are formed in one panel, and the cells are connected in series.

If a failure occurs in any one of these cells, the panel is not used and is discarded.

The embodiment provides a solar cell and a method of manufacturing the same that can be used as a solar cell even if a defective cell occurs.

A solar cell according to an embodiment includes: a plurality of solar cells formed on a substrate and including a back electrode pattern, a light absorbing layer, a buffer layer, and a front electrode layer; And a connecting electrode electrically connecting the back electrode pattern of the defective cell region among the solar cells, wherein the back electrode pattern of the defective cell region is exposed, and the exposed back electrode pattern is electrically connected. It includes.

A method of manufacturing a solar cell according to an embodiment includes forming a plurality of solar cells formed on a substrate and including a back electrode pattern, a light absorbing layer, a buffer layer, and a front electrode layer; Checking for defective cells of the solar cells; Exposing the back electrode pattern by removing the front electrode layer, the buffer layer, and the light absorbing layer of the defective cell region in which the defective cell is checked; Electrically connecting the back electrode pattern.

The solar cell and the method of manufacturing the same according to the embodiment can be used as a solar cell without discarding even if a defective cell is generated by connecting the defective cell region and adjacent cells to each other.

In the description of the embodiments, where each substrate, layer, film, or electrode is described as being formed "on" or "under" of each substrate, layer, film, or electrode, etc. , "On" and "under" include both "directly" or "indirectly" formed through other components. In addition, the upper or lower reference of each component is described with reference to the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation and does not mean the size actually applied.

7 is a cross-sectional view showing a solar cell according to an embodiment.

As illustrated in FIG. 7, the solar cell includes a first cell C1, a third cell C3, and a connection electrode 600, which are a plurality of solar cells formed on the substrate 100.

The plurality of solar cells C1 and C3 include a back electrode pattern 200, a light absorbing layer 300, a buffer layer 400, and a front electrode layer 500.

The connection electrode 600 is a defective cell region 370 formed between the first cell C1 and the third cell C3 to electrically connect the first cell C1 and the third cell C3. The back electrode pattern 200 is electrically connected.

The back electrode pattern 200 of the defective cell region 370 is exposed, and the connection electrode 600 connects the exposed back electrode pattern 200.

In the back electrode pattern 200 of the defective cell region 370, the defective cells and adjacent cells are electrically connected to each other by the connection electrode 600.

The connection electrode 600 is formed of a conductive material, and a part of the connection electrode 600 is formed to contact the substrate.

Hereinafter, the solar cell will be described in more detail according to the solar cell manufacturing process.

1 to 7 are sectional views showing the manufacturing process of the solar cell according to the embodiment.

First, as shown in FIG. 1, the back electrode pattern 200 is formed on the substrate 100.

The substrate 100 may be glass, and a ceramic substrate such as alumina, stainless steel, a titanium substrate, or a polymer substrate may also be used.

Soda lime glass may be used as the glass substrate, and polyimide may be used as the polymer substrate.

In addition, the substrate 100 may be rigid or flexible.

The back electrode pattern 200 may be formed of a conductor such as a metal, and may be formed by forming a conductive material and then patterning the conductive material.

For example, the back electrode pattern 200 may be formed by a sputtering process using a molybdenum (Mo) target.

This is because of high electrical conductivity of molybdenum (Mo), ohmic bonding with the light absorbing layer, and high temperature stability under Se atmosphere.

In addition, although not shown, the back electrode pattern 200 may be formed of at least one layer.

When the back electrode pattern 200 is formed of a plurality of layers, the layers constituting the back electrode pattern 200 may be formed of different materials.

In addition, the back electrode pattern 200 may be arranged in a stripe form or a matrix form and may correspond to each cell.

However, the back electrode pattern 200 is not limited to the above form and may be formed in various forms.

Subsequently, as shown in FIG. 2, the light absorbing layer 300 and the buffer layer 400 are formed on the back electrode pattern 200.

The light absorbing layer 300 may be formed of an Ib-IIIb-VIb-based compound.

In more detail, the light absorbing layer 300 includes a copper-indium-gallium-selenide-based (Cu (In, Ga) Se ₂ , CIGS-based) compound.

Alternatively, the light absorbing layer 300 may include a copper-indium selenide-based (CuInSe ₂ , CIS-based) compound or a copper-gallium-selenide-based (CuGaSe ₂ , CIS-based) compound.

For example, to form the light absorbing layer 300, a CIG-based metal precursor film is formed on the back electrode pattern 200 using a copper target, an indium target, and a gallium target.

Thereafter, the metal precursor film is reacted with selenium (Se) by a selenization process to form a CIGS-based light absorbing layer 300.

In addition, during the process of forming the metal precursor film and the selenization process, an alkali component included in the substrate 100 may pass through the back electrode pattern 200, and the metal precursor film and the light absorbing layer ( 300).

An alkali component may improve grain size and improve crystallinity of the light absorbing layer 300.

In addition, the light absorbing layer 300 may form copper, indium, gallium, selenide (Cu, In, Ga, Se) by co-evaporation.

The light absorbing layer 300 receives external light and converts the light into electrical energy. The light absorbing layer 300 generates photo electromotive force by the photoelectric effect.

The buffer layer 400 is formed of at least one layer, and any one or a stack of cadmium sulfide (CdS), ITO, ZnO, and i-ZnO on the substrate 100 on which the back electrode pattern 200 is formed. It can be formed as.

The buffer layer 400 may be formed of a transparent electrode.

In this case, the buffer layer 400 is an n-type semiconductor layer, the light absorbing layer 300 is a p-type semiconductor layer. Thus, the light absorbing layer 300 and the buffer layer 400 form a pn junction.

That is, since the difference between the lattice constant and the energy band gap is large between the light absorbing layer 300 and the front electrode, a good junction may be formed by inserting the buffer layer 400 having a band gap between the two materials.

In this embodiment, one buffer layer is formed on the light absorbing layer 300, but the present invention is not limited thereto. The buffer layer may be formed of two or more layers.

3, the contact pattern 310 penetrating the light absorbing layer 300 and the buffer layer 400 is formed.

The contact pattern 310 may be formed by a mechanical method or by irradiating a laser. A part of the back electrode pattern 200 may be formed by forming the contact pattern 310. Is exposed.

Subsequently, as shown in FIG. 4, the transparent conductive material is stacked on the buffer layer 400 to form the front electrode 500 and the connection wiring 350.

When the transparent conductive material is stacked on the buffer layer 400, the transparent conductive material may be inserted into the contact pattern 310 to form the connection wiring 350.

The back electrode pattern 200 and the upper electrode 500 are electrically connected to each other by the connection wiring 350.

The upper electrode 500 is formed of zinc oxide doped with aluminum by performing a sputtering process on the substrate 100.

The upper electrode 500 is a window layer forming a pn junction with the light absorbing layer 300. Since the upper electrode 500 functions as a transparent electrode on the front of the solar cell, zinc oxide (ZnO) having high light transmittance and good electrical conductivity is provided. Is formed.

In this case, an electrode having a low resistance value may be formed by doping aluminum to the zinc oxide.

The zinc oxide thin film that is the upper electrode 500 may be formed by a method of depositing using a ZnO target by RF sputtering, reactive sputtering using a Zn target, and an organometallic chemical vapor deposition method.

In addition, a double structure in which an indium tin oxide (ITO) thin film having excellent electro-optical properties is laminated on a zinc oxide thin film may be formed.

5, a separation pattern 320 penetrating the light absorbing layer 300 and the buffer layer 400 is formed.

The separation pattern 320 may be formed by a mechanical method, or may be formed by irradiating a laser, and may be formed to expose the top surface of the back electrode pattern 200.

The buffer layer 400 and the upper electrode 500 may be separated by the separation pattern 320, and the cells C1, C2, and C3 may be separated from each other by the separation pattern 320.

The buffer layer 400 and the light absorbing layer 300 may be arranged in a stripe shape or a matrix shape by the separation pattern 320.

The separation pattern 320 is not limited to the above form and may be formed in various forms.

Cells C1, C2, and C3 including the back electrode pattern 200, the light absorbing layer 300, the buffer layer 400, and the upper electrode 500 are formed by the separation pattern 320.

In this case, each of the cells C1, C2, and C3 may be connected to each other by the connection wiring 350.

That is, the connection wiring 350 electrically connects the back electrode pattern 200 of the second cell C2 and the upper electrode 500 of the first cell C1 adjacent to the second cell C2. do.

In addition, the connection wiring 350 electrically connects the back electrode pattern 200 of the third cell C3 and the upper electrode 500 of the second cell C2 adjacent to the third cell C3. do.

In addition, the plurality of solar cells C1, C2, and C3 separated by the separation pattern 320 are checked whether a defective cell has occurred.

The defective cell check may find a defective cell using a thermal imaging camera or the like on a panel on which the solar cells C1, C2, and C3 are formed.

If the second cell C2 is a defective cell, the first cell C1 and the third cell C3 connected in series are not connected to each other.

Thus, in the present exemplary embodiment, the first cell C1 and the third cell C3 are connected to each other so that even if a defect occurs in the solar cell, the cell can be used as a solar cell without disposal.

Subsequently, as illustrated in FIG. 6, the upper electrode 500, the buffer layer 400, and the light absorbing layer 300 of the second cell C2 are removed to form a defective cell region (the second cell C2). The lower electrode pattern 200 of 370 is exposed.

In this case, the upper electrode 500, the buffer layer 400, and the light absorbing layer 300 of the second cell C2 may be performed by a scribing process, but are not limited thereto and may be removed by an etching process. Can be.

The lower electrode pattern 200 exposed by removing the upper electrode 500, the buffer layer 400, and the light absorbing layer 300 of the second cell C2 is electrically connected to the adjacent first cell C1. In addition, the lower electrode pattern 200 is electrically connected to the third cell C3.

However, since the lower electrode pattern connected to the first cell C1 and the lower electrode pattern connected to the third cell C3 are separated from each other, the first cell C1 and the third cell C3 are electrically connected to each other. It is not connected to.

Thus, as shown in FIG. 7, the connection electrode 600 for electrically connecting the lower electrode pattern 200 is formed.

The connection electrode 600 may be formed so as not to be in contact with neighboring cells by filling a defective cell region, which is the second cell C2, with a conductive material and then performing a scribing process.

However, the method of forming the connection electrode 600 is not limited thereto, and may be formed by using an aluminum (Al) paste or a copper (Cu) paste, and also by using a mask, platinum (Pt). May be formed only on the lower electrode pattern 200 in the second cell C2 region.

The connection electrode 600 may be formed of a material such as aluminum (Al), copper (Cu), or platinum (Pt), but is not limited thereto.

The connection electrode 600 electrically connects the lower electrode pattern 200 of the defective cell area that is the second cell C2 to each other.

That is, the connection electrode 600 may electrically connect the first cell C1 and the third cell C3 adjacent to the second cell C2 which is a defective cell.

By electrically connecting the first cell C1 and the third cell C3, a series connection may be maintained.

In addition, the connection electrode 600 is formed to contact the substrate 100 while connecting the lower electrode pattern 200 to each other.

Therefore, by connecting the lower electrode pattern of the defective cell region to each other, the connection electrode 600 can use all other cells which are not defective, and can be used as a solar cell without discarding the defective cell.

As described above, the solar cell and the method of manufacturing the same according to the embodiment can be used as a solar cell without discarding even if a defective cell is generated by connecting the defective cell region and adjacent cells to each other.

Although described above with reference to the embodiment is only an example and is not intended to limit the invention, those of ordinary skill in the art to which the present invention does not exemplify the above within the scope not departing from the essential characteristics of this embodiment It will be appreciated that many variations and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

1 to 7 are cross-sectional views and plan views illustrating a manufacturing process of the solar cell according to the embodiment.

Claims (8)

A plurality of solar cells formed on the substrate and including a back electrode pattern, a light absorbing layer, a buffer layer, and a front electrode layer; And It includes a connection electrode for electrically connecting the back electrode pattern of the defective cell region of the solar cells, The back electrode pattern of the defective cell region of the solar cells is exposed, The exposed back electrode pattern includes a solar cell electrically connected. The method of claim 1, The back electrode pattern of the defective cell region includes a cell in which the defective cell and adjacent cells are connected to each other, and the defective cell and the adjacent cells are connected by a connection electrode. 3. The method of claim 2, The connection electrode is formed of a conductive material, A part of the connection electrode is in contact with the substrate, The connection electrode is a solar cell comprising any one of aluminum (Al), copper (Cu), platinum (Pt). Forming a plurality of solar cells formed on the substrate and including a back electrode pattern, a light absorbing layer, a buffer layer and a front electrode layer; Checking for defective cells of the solar cells; Exposing the back electrode pattern by removing the front electrode layer, the buffer layer, and the light absorbing layer of the defective cell region in which the defective cell is checked; The method of manufacturing a solar cell comprising the step of electrically connecting the back electrode pattern. The method of claim 4, wherein The front electrode layer, the buffer layer and the light absorbing layer of the defective cell region is removed by a scribing process. The method of claim 4, wherein The back electrode pattern is a manufacturing method of a solar cell comprising the electrically connected by a connection electrode. The method of claim 6, The back electrode pattern of the defective cell region, wherein the defective cells and adjacent cells are connected to each other, the defective cells and adjacent cells are connected to the connection electrode manufacturing method of a solar cell. The method of claim 6, The connection electrode is formed of a conductive material, A part of the connection electrode is in contact with the substrate, The connection electrode is a manufacturing method of a solar cell comprising any one of aluminum (Al), copper (Cu), platinum (Pt).

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